Plato’s theory of reality and knowledge were influenced under the idea of Parmenides. Both Plato and Parmenides of Elea have come into mutual agreements about the possible meaning of knowledge and reality. They have discussed, in their own individual works, the difference between appearance and reality; the nature of reality, also the criteria for Being; and the possibility of knowledge and the degrees of truth. All of these topics are deciphered in Parmenides’ poem and Plato’s Phaedo, Symposium, Republic, and Timaeus.
Pertaining to the distinction between appearance and reality, Parmenides of Elea said in his poem, “Truth / mortal opinions” (Parm. B8.50). This line implies that reality is the truth whereas mortal opinions indicate appearance. Appearance (mortal opinion) is believed, according to Parmenides, that it is not knowable because not every opinion is true and it cannot be reliable; just because you see and hear what you believed is true, doesn’t mean it is. On the other hand, reality (truth) is always true because it is unchanging. Comparing to Parmenides’ line, Plato quoted from his work Timaeus, “What is that which always is… that which becomes… the former [that which always is] is grasped by understanding… it is unchanging… the latter [that which becomes] is grasped by opinion… it comes to be and passes away” (Tim. 28a). Plato agreed to Parmenides; reality never changes whilst appearance always changes and therefore, the changing appearance will affect the individuals’ knowledge. In Phaedo, Plato said, “These latter you could touch and see and perceive with the other sense, but those that always remain the same can only be grasped by the reasoning power of the mind” (Pha. 7a)? This means that sensation and perception can be inaccurate when attempting to gain knowledge via appearance due to the fact it always alters. In contrast to this, thinking clearly and understanding (reasoning) is always the effective way to gain truth since reality never alters. An example of this would be that a shape with three sides is always a triangle and 2 plus 2 always equal to 4. In Republic, “What about the ones who in each case study the things themselves are always the same in every respect? Won’t we say that they know and don’t opine” (Rep. 479e) and “When it focuses on something illuminated by truth and what is, it understands, knows, and apparently possess understanding, but when it focuses on what is mixed with obscurity, on what it comes to be and passes away, it opines and is dimmed, changes its opinions this way and that, and seems bereft of understanding” (Rep. 508d). These lines from Plato clearly validates the idea that those who perceive reality (truth) are capable of understanding what is real and they habitually decline all opinions, whilst those who only perceive appearance (opinions) are incapable of understanding what is real as they incorrigibly accept altering opinions.
The nature of reality, also known as the criteria for Being, appears to be mutual for both Parmenides of Elea and Plato. In his poem, Parmenides said, “ungenerated / imperishable (not changing) / a whole of a single kind / complete / what-is ‘whole and changeless’ / ‘complete from all directions” (B8.3-45). Parmenides was saying that true reality is immortal (imperishable), as inn the never-changing truth never dies; if reality/Being never dies and is still around, then it does contain all the knowledge it provides for the learning individuals. The what-is is reality (metaphysical/ontology) itself, which is caused by thinking and knowing (epistemology). In Plato’s Republic, one relevant line says, “–the lover of sights who wouldn’t allow anyone to say that the beautiful itself is one or that the just is one or any of the rest…” (Rep. 479a). One line, from Plato’s Symposium, says, “…it always is and neither comes to be nor passes away… it is not beautiful this way and ugly that way, nor beautiful at one time and ugly at another…” (Sym. 211a). For Plato, it is believed that Beauty becomes reality as long as its knowledge is still around. First, there is one body, which is the beauty of form that turns into beautiful bodies that contains more valuable souls, which later participates into activities and customs (mainly thinking and knowing), which leads to knowledge; then knowledge turns into a “sea of beauty,” or spreads from one place to another, and that is where Beautiful reality comes from. This validates the idea that knowledge is provided by Beauty whenever there is thinking and knowing; no matter what kind of thinking and knowing one individual does depending on what he sees he assumes it’s Beautiful, it’s reality and Truth.
Lastly, Plato was under the influence of Parmenides as he discussed the theories of knowledge and the degrees or levels of truth. There are a few lines from Parmenides’ poem that are relevant to truth and knowledge: “well-persuasive Truth” and “beliefs of mortals” (Parm. B129-30); “path of persuasion” (Truth) / “path entirely unable to be investigated” (Parm. B2.3-6); and “neither can you know what is not… nor can you declare it” (Parm. B2.8). Parmenides was saying that just because what one senses, even under persuasion, doesn’t mean one cannot declare it as true in an instant. Perception on appearance doesn’t always mean it’s knowable; one cannot rely on appearance. In regards to Parmenides’ quotes from his poem, Plato’s Republic has several interesting lines about the theory of knowledge and truth: “Opinion, then, is set over one thing, and knowledge over another, according to the power of each” (Rep. 477b); “…opinion is clearly different from knowledge… knowledge is set over what is to know it as it is… and opinions opines” (Rep. 478a)?; and “…these people, we shall say, opine everything but have no knowledge of anything they opine” (Rep. 479a). Same goes to appearance, opinion is not knowable and cannot be relied on. When one opines and another sees and hears it, the latter would not be able to know the truth because the opinion from the former seems exaggerated. For one thing, opinion is from within what one proclaims is the truth. If it’s the truth, then how does he know? Therefore, Plato and Parmenides of Elea were saying that knowledge and truth only comes within the invisible world. In other words, instead of listening to opinions, which normally comes from the visible world, knowledge and truth would only be possible by logic and reasoning from the unchanging invisible world, such as mathematics (2 + 2 = 4) and geometry (all triangles have three sides), because it’s always true. Gaining knowledge from the changing visible world doesn’t add up; perception of appearance is mostly inaccurate because once it alters, the answers alters as well, which can affect the person’s mind.
Plato’s theory of reality and knowledge, after being inspired by the poem written by Parmenides of Elea, has taught the audience of where the meaning of intelligence comes from. For one thing, it’s clear that intelligence should only be formed by the unchanging invisible world because this is where Truth comes from and it’s always reliable. Another thing is that one should never be lectured by opining individuals; they would never know if what they said were in reality. Last thing, it’s crucial to understand that knowledge leads to reality and opinions are not reality. Opinions are unknowable and cannot be relied on. Overall, according to Plato and Parmenides, the theory of knowledge and reality, as well as thinking and knowing, most likely comes from the power of logic and reasoning, not by senses.
Sources:
Plato, Phaedo. pg. 101-139; Timaeus. trans. Donald J. Zeyl. Hackett Publishing Company, Indianapolis/Cambridge; Symposium. excerpts; and The Republic. Books V an VI. excerpts.
Parmenides of Elea, Poem of Parmenides.
Parmenides of Elea, Poem of Parmenides